As one of techniques for realizing, lightness, low power consumption and highly sophisticated function of recent electronic devices, the technique of micro-electromechanical systems (MEMS) has received much attention. The MEMS is a system having a smaller mechanical element and electronic circuit element combined by a silicon process technique.
An electrostatic actuator using MEMS is used in a radio-frequency (RF) MEMS variable capacitor or RF-MEMS switch. For example, the electrostatic actuator includes a lower electrode, an upper electrode and an insulating film disposed between the electrodes. In order to shift the electrostatic actuator from an up state to a down state, a potential difference is applied between the lower electrode and the upper electrode to drive the upper electrode.